netdev - Re: [PATCH net-next 0/3] net: phy: broken turn-around support

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Message-ID: <555268F8.4030109@gmail.com>
Date:	Tue, 12 May 2015 13:56:24 -0700
From:	Florian Fainelli <f.fainelli@...il.com>
To:	Bert Vermeulen <bert@...t.com>, netdev@...r.kernel.org
CC:	davem@...emloft.net, jogo@...nwrt.org
Subject: Re: [PATCH net-next 0/3] net: phy: broken turn-around support

On 12/05/15 13:43, Bert Vermeulen wrote:
> On 05/12/2015 07:33 PM, Florian Fainelli wrote:
>> Hi all,
>>
>> This is an attempt at solving the broken turn-around problem in a way that
>> is not specific to the mdio-gpio driver, since it affects different kinds of
>> platforms.
>>
>> We cannot make that localized to PHY device drivers because probing the PHY
>> device which has a broken turn-around can fail as early as in get_phy_id(),
>> therefore we need a bit of help from Device Tree/platform_data.
> 
> That is indeed a better place to put that ignore-ta flag, and the device
> tree support is of course a big improvement over the previous patch as well.
> 
> But it's still too big a hammer to hit the AR8316 problem with, I think.
> Just like the previous patch, this disables checking TA on _all_ reads, but
> I really only need it disabled on the first read.
> 
> Are you saying you've seen other systems with this TA problem? Did those
> have problems after more than just the first read?

Yes, I have a bunch of boards here that use a Broadcom BCM53125 switch
which is known not to release the line during turn-around time, and that
is for all reads. A workaround is to discard the read failure indication
from the MDIO controller, but to selectively do that, I would be keen on
using the patches I just posted.
-- 
Florian
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